1. Field of the Invention
The present invention relates to a hardcoat film, an antireflection film, and an equipment for display. More particularly, the present invention relates to a hardcoat film and an antireflection film for use on the surface of a display screen and a polarizer as well as to an equipment for display including the antireflection film.
2. Description of the Related Art
Plastic films such as polyester films have excellent mechanical properties, dimensional stability, heat resistance, transparency, and electrical insulating properties. They are widely used as substrates for many applications including magnetic recording materials, packaging materials, electrical insulating materials, photographic materials, graphic art materials and optical display materials.
However, plastic films generally have low surface hardness and insufficient abrasion resistance. Therefore, the surfaces such plastic films are easily damaged by friction or scratching due to contact with other stiff materials. The damage generated on the surface may significantly decrease the commercial value of the film, or make the film unusable for a shortened period.
In order to solve this problem, a hardcoat layer having excellent scratch resistance and abrasion resistance is disposed on the substrate film comprising polyester.
The hardcoat layer has a different refractive index from that of a polyester substrate or primer layer, and a distinct interface caused by the difference in the refractive indices exists between the hardcoat layer and the substrate or the primer layer. The film has a decreased clear view property, i.e., glittering or partly iris-like reflection is generated when the film is viewed at an angle. In order to avoid this phenomenon, various countermeasures have been taken. For example, Japanese Unexamined Patent Application Publication No. 2002-241527 discloses that a difference in refractive indices is decreased by improving the coating thickness accuracy and increasing the refractive index of the hardcoat layer. Japanese Unexamined Patent Application Publication No. 8-197670 discloses that a surface of a substrate film is roughened by embossing using a thermal press method and a hardcoat layer is laminated thereon. Japanese Unexamined Patent Application Publication No. 2003-205563 discloses that a solution for dissolving a substrate film is used for a hardcoat to dissolve or swell the substrate, thereby decreasing the interference fringe.
A conventional antireflection film including a hardcoat film is used as a display for a television display and a computer monitor. External light such as sunlight and fluorescent light are reflected and entered on/into the display to decrease a clear view property.
In order to prevent the light reflection, irregularities are provided on the surface of the display to diffuse the external light, or high and low refractive index thin films are alternately laminated on the display.
However, diffusion of the external light is insufficient for improving the clear view property, since images on the display are blurred.
Japanese Unexamined Patent Application Publication Nos. 4-355401 and 11-174971 discloses that a low refractive index layer is formed on a surface of a display to decrease the surface reflectance. However, the low refractive index layer is made of fluorine-containing resin, and therefore has insufficient surface hardness and scratch resistance. The surface is gradually scratched upon cleaning to decrease the clear view property.
Japanese Unexamined Patent Application Publication Nos. 2001-167637 and 2003-201443 disclose a low refractive index layer containing hollow particles for antireflection.
However, the reflectance is still not sufficiently decreased, interference iris pattern is produced, and scratch resistance of the surface does not satisfy the sufficient level.